Movements of the Temporomandibular Joint Disk

The etiology of temporomandibular joint (TMJ) disorders, including osteoarthritis, is largely unexplained. TMJ disk integrity is crucial, as its failure appears to precede degeneration of the joint. During mandibular function, the TMJ disk undergoes displacements and deformations, generating strains and stresses. Dynamic stereometry, a combination of imaging and jaw tracking, yields a noninvasive, 3-dimensional, and dynamic representation of the relationship between the articular surfaces of the human TMJ. The aim of this study was to refine this method to depict also movement and deformation of the TMJ disk during jaw opening/closing. Data collected in 4 asymptomatic subjects (2 male and 2 female subjects, aged between 24 and 32 years) indicated large disk displacements and deformations that can load TMJ soft tissues during opening and closing of the jaw. Such displacements and deformations can trigger disk damage during dysfunctional loading and/or compromised state of TMJ tissues. These displacements and deformations can also be used for numerical joint modeling.